NH NH2 Research Articles

Hydrazine Sulfonic Acid, NH3 NH(SO3 ), the Bigger Sibling of Sulfamic Acid.

The reaction of hydrazine hydrate, N2 H4 ⋅ H2 O, and SO3 leads to hydrazine sulfonic acid (Pca21 , a=849.59(4) pm, b=482.18(2) pm, c=832.17(4) pm). Structure elucidation reveals the zwitter-anionic nature of the compound according to NH3 NH(SO3 ). With the barium salt Ba[NH2 NH(SO3 )]2 (H2 O), a first salt of hydrazine sulfonic acid has been prepared (P , a=489.75(5) pm, b=737.52(7) pm, c=1317.4(1) pm, α=88.238(4)°, β=84.761(4)°, γ=79.701(4)°). The compounds were characterized by vibrational spectroscopy, DFT calculations and thermal analyses.

Highly selective detection of formaldehyde and its analogs in clams based on unique and specific conjugation reactions via ultraviolet-visible absorptions

Although formaldehyde has been widely used in industry, the excessive or residual formaldehyde has been proven to cause irreversible harm to human beings due to its high toxicity. To solve this problem, we studied oxalyldihydrazide as an analytical reagent to determine formaldehyde by ultraviolet and visible (UV-vis) spectrophotometry. In this study, hydrazine compounds with –NH–NH2 structures can react with formaldehyde to form hydrazone (including –NH–N=CH–), water is the only by-product. Therefore, oxalyldihydrazide can not only react with formaldehyde but also sense its analogs such as acetaldehyde, acetone, and benzaldehyde in solution, and detect them by UV-vis spectrophotometry at 220 nm, 226 nm, 262 nm, and 257 nm respectively. Among them, the limit of detection (LOD) of formaldehyde is calculated to be 0.03 ppm (LOQ = 0.03 ppm) with the relative standard deviation (RSD) of 1.58%. Meanwhile, the above-mentioned method can be used for detecting formaldehyde in clams with excellent selectivity and sensitivity.

Molecular and Electronic Structures of Macrocyclic Compounds Formed at Template Synthesis in the M(II)-Thiocarbohydrazide-Diacetyl Triple Systems: A Quantum-Chemical Analysis by DFT Methods.

Using density functional theory (DFT) B3PW91/TZVP, M06/TZVP, and OPBE/TZVP chemistry models and the Gaussian09 program, a quantum-chemical calculation of geometric and thermodynamic parameters of Ni(II), Cu(II), and Zn(II) macrotetracyclic chelates, with (NNNN)-coordination of ligand donor centers arising during template synthesis between the indicated ions of 3d elements, thiocarbohydrazide H2N-HN-C(=S)-NH-NH2 and diacetyl Me-C(=O)-C(=O)-Me, in gelatin-immobilized matrix implants was performed. The key bond lengths and bond angles in these coordination compounds are provided, and it is noted that in all these complexes the MN4 chelate sites, the grouping of N4 atoms bonded to the M atom, and the five-membered and six-membered metal chelate rings are practically coplanar. NBO analysis of these compounds was carried out, on the basis of which it was shown that all these complexes, in full accordance with theoretical expectations, are low-spin complexes. The standard thermodynamic characteristics of the template reactions for the formation of the above complexes are also presented. Good agreement between the data obtained using the above DFT levels is noted.

A multifunctional additive strategy to stabilize the precursor solution and passivate film defects for MA-free perovskite solar cells with an efficiency of 22.75%

Though great progress has been realized in perovskite solar cells (PSCs), there are still some thorny challenges that exist such as 1) low power conversion efficiency (PCE) and loss of stability due to the defects in the film; 2) poor reproducibility of solution-processed PSCs due to the unstable perovskite precursor solution. Here, an effective multifunctional additive, benzoyl hydrazine (BH), was developed to modify the perovskite film. The result shows that the defect of the film decreased after BH modification due to the interaction between BH and perovskite. Meanwhile, the I ions (I−) migration is also suppressed due to the weak interaction between BH and perovskite. In addition, the –NH–NH2 in BH can reduce the undesired I2 by reducing it to I−. Finally, the PCE of PSCs modified by BH achieved a PCE of 22.75%, which is one of the highest PCE of the reported MA-free PSCs. The modified device still exhibited excellent stability in different conditions.

Electrochemical ammonia synthesis via nitrogen reduction reaction on 1T/2H mixed-phase MoSSe catalyst: Theoretical and experimental studies

Electrocatalytic nitrogen reduction (NRR) is regarded as an energy-efficient technology to produce NH3. Nevertheless, achieving high NH3 yield and Faradaic efficiency (FE) under ambient conditions remains a great challenge. Herein, 1T/2H mixed-phase MoS0·5Se1.5 (named 1T/2H MoSSe) nanoflower, as an efficient non-noble metal NRR electrocatalyst, was synthesized by the one-step solvothermal method. 1T/2H MoSSe realizes an excellent NH3 yield of 32.32 μg h−1 mgcat.−1 at −0.45 V vs. RHE and an outstanding FE of 12.66% at −0.40 V vs. RHE in 0.1 M HCl, which are better than pure MoS2 (NH3 yield: 15.16 μg h−1 mgcat.−1, FE: 0.35%) and MoSe2 (NH3 yield: 26.42 μg h−1 mgcat.−1, FE: 2.75%). Density functional theory (DFT) calculations exhibit that MoSSe catalyst is structurally favorable to the potential-determining step (PDS, *NH–NH2 → *NH2–NH2) and thus shows increased NRR activity and selectivity. A promising tactic for the rational design of economical, efficient, and durable NRR electrocatalysts is proposed in this work.

Dual-crosslinked hyaluronic acid hydrogel with self-healing capacity and enhanced mechanical properties

Self-healing hydrogels can repair their cracks, and restore their original properties. However, self-healing hydrogels usually face low mechanical strength and poor stability. By the dual crosslinking strategy, a self-healing hyaluronic acid-based hydrogel with enhanced strength was fabricated by dynamic acylhydrazone linkages between aldehyde-modified maleic sodium hyaluronate and 3,3′-dithiobis (propionylhydrazide) and subsequent photopolymerization among maleic groups in the hydrogel network. The hydrogels exhibit fast gelation and excellent self-healing capability due to the dynamic and reversible characteristics of acylhydrazone and disulfide linkages. Furthermore, the dual crosslinking increase the mechanical strength of the hydrogels and prolong their stabilization time. Swelling behaviors, morphology, and mechanical properties could be adjusted by altering the molar ratio of –NH–NH2/–CHO. Besides, the hydrogels displayed interesting pH-responsiveness and cytocompatibility. The hydrogels have potential applications in cell culture, drug delivery, and 3D bioprinting.

Interfacial Embedding for High‐Efficiency and Stable Methylammonium‐Free Perovskite Solar Cells with Fluoroarene Hydrazine

AbstractPerovskite solar cells (PSCs) with state‐of‐the‐art efficiencies contain thermally unstable methylammonium (MA). Here, interfacial passivation with pentafluorophenylhydrazine (5F‐PHZ) to fabricate efficient and stable MA/Br‐free PSCs is introduced. The 5F‐PHZ surface treatment quenches the PbI2 and δ‐perovskite phase formed in the pristine film. The surface passivation ameliorates the film chemistries at the surface with modulation of interface band alignment as a consequence of halogen bonding with fluoroarene moieties or NH–NH2 terminals. This results in a much longer carrier lifetime with the passivation at the surface and grain boundaries trap centers. As a result, it boosts the power conversion efficiency (PCE) (area ≈ 1 cm2) from 18.10% to 22.29% (VOC ≈ 1.096–1.178 V) with superior operational thermal stability. A certified PCE of 21.01% with a large area of ≈1.026 cm2 is also achieved. It is found that the surface passivation forms an interfacial embedded layer subsequent to attenuation of defect densities and suppression of ion migration, which is supported by density‐function‐theory calculation. Importantly, this approach is effective in enhancing the PCE of narrow and wide bandgap perovskite systems. Thus, this work opens up a new technique for interface modulation with fluoroarene functional derivatives to achieve superior device performance and stability.

Numerical investigation of the effects of H2/CO/syngas additions on laminar premixed combustion characteristics of NH3/air flame

Co-firing NH3 with H2/CO/syngas (SYN) is a promising method to overcome the low reactivity of NH3/air flame. Hence, this study aims to systematically investigate the laminar premixed combustion characteristics of NH3/air flame with various H2/CO/SYN addition loadings (0–40%) using chemical kinetics simulation. The numerical results were obtained based on the Han mechanism which can provide accurate predictions of laminar burning velocities. Results showed that H2 has the greatest effects on increasing laminar burning velocities and net heat release rates of NH3/air flame, followed by SYN and CO. CO has the most significant effects on improving NH3/air adiabatic flame temperatures. The H2/CO/SYN additions can accelerate NH3 decomposition rates and promote the generation of H and NH2 radicals. Furthermore, there is an evident positive linear correlation between the laminar burning velocities and the peak mole fraction of H + NH2 radicals. The reaction NH2 + NH <=> N2H2 + H and NH2 + NO <=> NNH + OH have remarkable positive effects on NH3 combustion. The mole fraction of OH × NH2 radicals positively affects the net heat release rates. Finally, it was discovered that H radicals play an important role in the generation of NO. The H2/CO/SYN additions can reduce the hydrodynamic and diffusional-thermal instabilities of NH3/air flame. The NH3 reaction pathways for NH3–H2/CO/SYN-air flames can be categorized mainly into NH3–NH2–NH–N–N2, NH3–NH2–HNO–NO(−N2O)–N2 and NH3–NH2(−N2H2)–NNH–N2. CO has the greatest influence on the proportions of three NH3 reaction routes.

Asymmetric Transfer Hydrogenation of Ketones with Well-Defined Manganese(I) PNN and PNNP Complexes

Three new manganese complexes trans-[Mn(P–NH–NH–P)(CO)2][Br], (14) P–NH–NH–P = (S,S)-PPh2CH2CH2NH–CHPhCHPhNHCH2CH2PPh2), fac-[Mn(P′–NH–NH2)(CO)3][Br], (15) P′–NH–NH2 = (S,S)-PPh2(C6H4)NHCHPhCHPhNH2, and syn-mer-Mn(P–NH–NH2)(CO)2Br, (16) P–NH–NH2 = (S,S)-PPh2CH2CH2NHCHPhCHPhNH2 were synthesized and tested for the asymmetric transfer hydrogenation (ATH) of acetophenone in 2-PrOH. The ligands have stereogenic centers derived from the starting diamine, (S,S)-DPEN. Complex 16 was shown by NOE NMR experiments to have Mn–Br syn to the N–H of the secondary amine. Only the precatalyst 16, upon reaction with potassium tert-butoxide (KOtBu) in 2-PrOH, generated an active system at 80 °C for the ATH of acetophenone to 1-phenylethanol in an enantiomeric excess (ee) of 42% and thus was selected for further investigation into the mechanism of transfer hydrogenation. The corresponding amido complex Mn(P–N–NH2)(CO)2 (17), a borohydride complex syn-mer-Mn(P–NH–NH2)(CO)2(BH4) (18), and an ethoxide complex anti-mer-Mn(P–NH–N...

Effects of surface charge, hydrophilicity and hydrophobicity on functional biocathode catalytic efficiency and community structure

The bioelectrotransformation efficiency of various organic matters and corresponding electrode biofilm community formation as well as electron transfer efficiency in bioelectrochemical systems (BESs) with different modified electrodes has been extensively studied on the anode side. However, the effects of cathode interface characteristics towards the BESs bioelectrotransformation performance remain poorly understood. In this study, the nitrobenzene-reducing biocathode catalytic efficiency and community structure in response to different modified electrodes (control: hydrophobic and no charge; –SH: hydrophobic and single negative charge; –NH2: hydrophilic and single positive charge –NH–NH2: hydrophilic and double positive charges) were investigated. The biocathode transformation efficiency of nitrobenzene (NB) to aniline (AN) (ENB-AN) was affected by the nature of electrode interface as well as the biocathode community formation and structure. Cathodes with hydrophilic surface and positive charges have performed well in the bioelectrotransformation experiments, and especially made an outstanding performance when inorganic NaHCO3 was supplied as carbon source and cathode as the sole electron donor. Importantly, the hydrophilic surfaces with positive charges were dominated by the electroactive nitroaromatic reducers (Enterococcus, Desulfovibrio and Klebsiella) with the relative abundance as high as 72.20 ± 1.87% and 74.86 ± 8.71% for –NH2 and –NH–NH2 groups respectively. This could explain the higher ENB-AN in the hydrophilic groups than that of the hydrophobic –SH modified group. This study provides new insights into the effects of electrode interface characteristics on the BESs biocathode performance and offers some suggestions for the future design for the improvement of bioelectroremediation performance.

Molecular structures of (575)macrotricyclic 3d-metal chelates in M(II)–N-methylthiocarbohydrazide–hexanedione-2,5 according to density functional theory calculations

The geometric parameters of the molecular structures and thermodynamic parameters of macrotricyclic M(II) (M = Mn, Fe, Co, Ni, Cu, Zn) complexes with an MN2S2 chelate core formed by the template reactions of the M(II) with N-methylthiocarbohydrazide H3C–HN–HN–C(=S)–NH–NH2 and hexanedione- 2,5 H3C–C(=O)–CH2–CH2–C(=O)–CH3 have been calculated by the DFT method with the Gaussian09 program package. The bond lengths, bond angles, and some nonbonded angles in these complexes have been determined. In all the complexes, the M(II) central ion is pseudotetrahedrally coordinated by the donor atoms of an inner-sphere tetradentate ligand; the (N2S2) group of the donor atoms is not planar. The additional seven-membered chelate rings show significant deviations from coplanarity (>60°). The noncoplanatiry of the five-membered rings is less pronounced.

Synthesis, structure, and biological properties of mixed cobalt(III) dioximates with guanidine derivatives

Two Co(III) dioximates, cyanoguanidine complex {[Na2(µ-H2O)2(L1)2(H2O)2]-[CoIII(DmgH)2(N3)2]} n [CoIII(DmgH)2(N3)2] n (L1 = (H2N)2C=N–C=N) (I) and aminoguanidine complex [H3L2][Co(DmgH)2(N3)2] (H2L2 = H2N–C(=NH)–NH–NH2) (II), were synthesized from the [CoCl(DmgH)2(H2O)] structural unit (DmgH– is the dimethylglyoxime monoanion). The implementation of the synthesis was confirmed by chemical analysis, IR spectroscopy, and X-ray diffraction (CIF files CCDC 1531845 (I), 1531846 (II)). Both compounds are ionic. Compound I consists of cations representing centrosymmetrical 2D coordination polymers, {[Na2(µ-H2O)2(L1)2(H2O)2][CoIII(DmgH)2(N3)2]} n+ n , and monomeric [Co(DmgH)2(N3)2]– anions, while in II, the charge of the [Co(DmgH)2(N3)2]– complex anion is counterbalanced by the organic [H3L2]+ cation. In I, L1 is coordinated to the metal as a monodentate neutral ligand, while in II, H2L2 occurs in the complex as a protonated uncoordinated component. Since L1 in I and H2L2 in II contain functional amine groups able to form intermolecular hydrogen bonds acting as proton donors, the component packing mode in the crystals was analyzed assuming various types of interactions, apart from electrostatic ones. The biological properties of the complexes were tested considering their effect on the biosynthesis of proteases by the micromycete Fusarium gibbosum CNMN FD 12 strain. Culturing the producer on a culture medium containing complex I in the selected optimal concentrations of 5–10 mg/L was found to increase the acid protease activity by 140–150%.

Transition-Metal Catalyst Free Oxidative Radical Arylation of N-Methylpyrrole.

This study represents an expansion of the application of catalysis in air through conventional coupling and free radical processes. A reactive free aryl radical intermediate was generated via the oxidation of an activated Ar–NH–NH2 bond by air as a simple and readily available oxidant. For this purpose, the usability of phenylhydrazine and phenylhydrazine hydrochloride salt reagents for the direct arylation of pyrrole with aryl radicals was investigated. The facile coupling of N-methylpyrrole with aryl radicals was easily applied for the convenient direct synthesis of C-2 arylated pyrroles without a transition-metal catalyst.

Phosphorhydrazides as urease and acetylcholinesterase inhibitors: biological evaluation and QSAR study

New phosphorhydrazide compounds (1–7, 13, 15–16) and thiophosphorhydrazide (14 and 17) were synthesized and characterized by 31P, 13C, 1H NMR and IR spectroscopy. Furthermore, the crystal structure of compound (C6H5NH)(C6H5O)P(O)(NH–NH2) (2) was investigated. The activities of derivatives on acetylcholinesterase (AChE) and urease were determined. Quantitative structure–activity relationship (QSAR) was used to understand the relationship between molecular structural features and inhibitory. DFT–QSAR models for enzymes demonstrated the importance of E LUMO parameter in describing the anti-AChE and anti-urease activities of the synthesized compounds. The correlation matrix of QSAR models and docking analysis confirmed that electrophilicity descriptor can control the influence of the polarizability properties of N–H functional group of PAH derivatives in the inhibition of enzymes.

Sulfonated Poly(Fluorenyl Ether Ketone) Membranes with Suppressed Semi-Interpenetrating Crossover and Enhanced Proton Selectivity for Vanadium Redox Flow Batteries

A series of hybrid membranes with special microstructure, based on sulfonated poly (fluorenyl ether ketone) ionomer (SPFEK, IEC=1.74 mequiv.g-1) and secondary amine group containing SiO2 (SiO2–NH–NH2), has been successfully designed and prepared for vanadium redox flow battery (VRB) application. The hybrid membranes are prepared by simply adding KH792 into the SPFEK solution in N,N’-dimethylacetamide (DMAc), followed by dispersion, co-condensation and solvent casting. The water uptake, mechanical property, proton conductivity, (VO)2+ permeability and single cell performance are investigated in order to understand the relationship between morphology and property of the membranes. The hybrid membranes show dramatically improved proton selectivity when compared with SPFEK. The vanadium ion (VO)2+ permeability through the hybrid membrane is about 10 times lower than that of virgin SPFEK. The columbic efficiency and energy efficiency of the single cell of the hybrid membrane are higher than the SPFEK membrane. The results inidicate that hybrid membranes of this type are promising for VRBs.

The decomposition of α-LiN2H3BH3: an unexpected hydrogen release from a homopolar proton–proton pathway

The intermolecular interactions of N–H⋯B–H (proton–hydride) have been considered to mediate the release of hydrogen from B–N-based complexes. Mass spectroscopy studies on the thermal decomposition of isotopomer α-LiN2H3BD3, however, indicate that the initial dehydrogenation occurs through a homopolar N–H⋯H–N (proton–proton) pathway, followed by the N–H⋯B–H (proton–hydride) and B–H⋯B–H (hydride–hydride) pathways. The unexpected scission of the N–H bonds prior to B–H bonds can be attributed to the molecular structure of Li[NH2–NH–BH3], in which the detachment of the (N)H atoms results in a significant reduction of the N–N and N–B bond length, hence reducing the (N)H detachment energy. The scission of N–H bonds further facilitates the detachment of the (B)H atom, therefore, promoting the following proton–hydride and hydride–hydride dehydrogenation pathways.

Synthesis, crystal structures, antimicrobial activities, and DFT calculations of two new azido nickel(II) complexes

Two new complexes, [Ni(HL1)(N3)(μ1,1N3)]2 (1) [HL1: NC5H4CH3C=NNH (C=O) NH2] and [Ni(L2)N3] (2) [HL2: NC5H4HC=N NH(C=S)NH2], have been synthesized by reaction of Ni(OAC)2·4H2O and sodium azide with HL1 and HL2 and characterized by elemental analysis, FT-IR, and UV–vis spectral studies. Single-crystal X-ray diffraction reveals that 1 is dinuclear with nickel(II) in an octahedral environment of NNO donors of HL1, two nitrogens of azide bridges and one nitrogen of terminal azide; 2 is mononuclear containing nickel(II) in a distorted square-planar environment of NNS donors of HL2 and one terminal azide. The structures of 1 and 2 have been optimized by density functional theory. The results of antimicrobial activities of ligands, 1 and 2 demonstrated that HL2 and 2 have good antimicrobial activity in contrast with HL1 and 1, related to the presence of sulfur donor in HL2.

A comparative study of radical cations of thiourea, thiosemicarbazide, and diethylthiourea in aqueous sulphuric acid media employing pulse radiolysis technique

The generation of radical cations of thiourea [(NH2)2C=S], thiosemicarbazide [(NH2―NH)(NH2)C=S], and diethylthiourea [(C2H5―NH)2C=S] in aqueous sulphuric acid media of low to high acid strengths utilizing the pulse radiolysis technique is reported. In this system, the decay half‐life of radical cations of thiourea and its derivatives observed were longer (ranging from 45 to 100 µs at acid strength pH/H0 = −4.1), and the formation times could be altered with the change in acid strengths. By doing so, a wide range in half‐life of radical cations of thiosemicarbazide (0.7 to 100 µs) was observed in contrast to thiourea and diethylthiourea with the variation in acid strengths (pH/H0) from 0.7 to −4.1. This perhaps helps in studying the spectral and kinetic properties of transient radical cations comfortably. The general mechanism for the formation of radical cations of the aforementioned compounds in radiolysis has been revisited in which the electron transfer reactions are active. Copyright © 2013 John Wiley &amp; Sons, Ltd.

GGA-based analysis of the metformin adsorption on BN nanotubes

Density functional theory (DFT) studies are done to investigate structural and electronic properties of (5,5) chirality single walls boron nitride nanotubes (BNNTs) in the armchair model interacting with metformin (MF) on the surface and ends. Our calculations consider the exchange-correlation energies with the Hamprecht–Cohen–Tozer–Handy functional within the generalized gradient approximation (HCTH-GGA) and the double polarized DNP base function. The geometry optimization follows the minimum energy criterion for all six geometries we have considered. Results show that the MF is adsorbed through the groups NH2–NH at one end of the nanotube. The system polarity is increased which indicates the possible dispersion and solubility. Moreover the interaction between these species induces an increase in the chemical reactivity of the order of 0.42eV. Meanwhile the solvation in water keeps the semiconductor characteristics of both nanotube and MF. The work function of the BNNT-MF is drastically reduced respect to the pristine system when the BN nanotube is doped at its surface and ends with carbon. This means that the functionalized BN nanotube facilitates conditions to improve field emission.

Phosphorylated glucosamine inhibits adipogenesis in 3T3-L1 adipocytes

Phosphorylated glucosamine (glucosamine-6-phosphate, PGlc) was synthesized using methanesulfonic acid, phosphorus pentoxide (P 2O 5), NH 2NH 2 and DMF. Its inhibitory effect on lipid accumulation in cultured 3T3-L1 adipocytes was investigated by measuring triglyceride contents and Oil Red O staining. In order to understand the mechanism by which lipid accumulation in adipocytes is decreased by PGlc, we examined the expression levels of several genes and proteins associated with adipogenesis and lipolysis using reverse transcription polymerase chain reaction, real-time polymerase chain reaction and Western blot analysis. Treatment with PGlc significantly reduced lipid accumulation during adipocyte differentiation and induced down-regulation of peroxisome proliferator-activated receptor-γ, sterol regulatory element binding protein 1 and CCAAT/enhancer binding protein-α in a dose-dependent manner. Moreover, treatment with PGlc during adipocyte differentiation induced significant up-regulation of preadipocyte factor 1 mRNA and down-regulation of such adipocyte-specific gene promoters as adipocyte fatty acid binding protein, fatty acid synthase, lipoprotein lipase and leptin. According to the lipolytic response, PGlc up-regulated hormone-sensitive lipase mRNA expression and suppressed the expression levels of tumor necrosis factor-α mRNA compared with fully differentiated adipose tissue. These results suggest that the inhibitory effect of PGlc on adipocyte differentiation might be mediated through the down-regulation of adipogenic transcription factors, such as peroxisome proliferator-activated receptor-γ, sterol regulatory element binding protein 1 and CCAAT/enhancer binding protein-α, which are related to the downstream adipocyte-specific gene promoters.